Apparatus for pressuring air counterbalance cylinders



Jan. 3, 1950 w. G. COREY 2,493,341

APPARATUS FOR PRESSURING AIR COUNTERBALANCE CYLINDERS Filed Aug. 2, 19482 sheets sheet 1 FIG. I WILLIAM QCQREY lNl ENTOR A 7' TORNEV Jan. 3,1950 w. G. COREY 2,493,341

APPARATUS FOR PRESSURING AIR COUNTERBALANCE CYLINDERS Flled Aug. 2, 19482 Sheets-Sheet 2 2/ as m Fl 6. 2

w w M |||||1 1 Fa i'iu' 33 7 a7 a? 57 WILLIAM G. COREY A fron/vgrPatented Jan. 3, 1950 UNITED STATES PATENT OFFICE APPARATUS FORPRESSURING AIR COUNTERBALANCE CYLINDERS William G. Corey, Altadena,Calif.

Application August 2, 1948, Serial No. 42,104

3 Claims. 1

This invention relates tothe pumping of deep wells with the use of anair counterbalance, and in particular to means for supplying thecounterbalance cylinder with make-up air and for repressuring thecylinder after periods of inactivity during which the pressure normallycarried in it is vented.

A purpose of the invention is to permit the compressor supplyingv airunder pressure to the cylinder to be driven by the prime mover by whichthe beam is activated, both with the beam in motion and with the beamidle.

A purpose of the invention is to provide automatic means forinactivating the compressor when the pressure in the air cylinderreaches a predetermined level.

In the operationof an air-balanced pumping unit, as described forexample in the patent to Brett, l,624,52'1,'which is continuous overlong periodamake-up air is required at intervals to replace leakage. Thequantities so required are very small and a correspondingly smallcompressor is required. But when the unit is shut down, as for exampleto pull rods, the pressure within the cylinder may leak off, or bevented completely before the unit is again put into service, and beforeagain starting the well pump the cylinder must be recharged to itsoriginal pressure. To save loss of pumping time, which is highlyvaluable, it is desirable to recharge as rapidly as possible, and thus alarge delivery of compressed air for a'short period is needed.

While numerous devices for providing makeup and repressuring air havebeen proposed, the only one which has come into general use is thatshownin the Brett patent and in many others of later date. In'thesedevices a single acting, reciprocating compressor has one of itselements coupled to and moving, with the beam and the other elementcoupled to a fixed object, the compression stroke being produced by thedownward movement of the beam. As such compressors stroke continuouslyso long as the beam is in operation, it is customary to provide meansfor unloading thennaszby lifting: the intake valve from its seat, whenthe desired cylinder pressure has been reached.

This device may be so designed as to give satisfactory service insupplying the small amount of make-up air required to offset leakage,but whenmade of suflicient size to repressure the empty cylinder withina reasonable time, it becomes cumbersome, costly and difficult tomaintain because it idles the greater part of the time.

The main drawback, however, to the use of any beam-operated compressoris that the beam must be operated in order to operate the compressor.This requires that the counterbalance cylinder be valved off so as notto create excessive loads on the unit as the system pressure approachesthe required counterbalancing pressure. Or, by a complicated arrangementof piping and valves the counterbalance cylinder is converted into anauxiliary compressor to help the repressuring operation. The resultinglong time, single-stage compression generates excessive heat and, in thenecessary presence of lubricating oil, often causes the explosion of oilvapors in the cylinder, with hazard to machine and operators alike.

In the apparatus of the instant invention, a small independentcompressor is driven at a relatively high speed from the prime moverduring the pumping up period, the beam being then disconnected; the beamis reconnected only after the cylinder is fully repressured and itscounterbalancing effect reestablished; the compressor operates at alower speed for providing make-up air, and automatic means are providedfor disconnecting the compressor from its drive when the desiredpressure is reached.

The invention may best be understood with ref erence to the attacheddrawings and the following' description thereof, in which Fig. l is anelevation of an air balanced pumping unit (a portion of thecounterbalancing cylinder being shown in section) showing the relativearrangement of parts with which the invention is concerned, and

Fig. 2 is a detail on an enlarged scale of the drive from prime mover toreducing gear and air compressor.

Referring first to Fig. l, foundation members ill support samson posts Hwhich are braced against overturning as at l2. A beam !3 is pivotallysupported as at M and is reciprocated around this pivot point by cranksit and p-itmans i6, only one of each showing in the figure. The outer orright-hand end of the beam is provided with a horsehead and cable, notshown, or other meansv for attaching the pump rod string to the swingingend of the beam.

The cranks are powered by any preferred prime mover, as for example thegas engine suggested at IT. This engine has a pulley [8 driving acorresponding pulley !9 mounted on the high speed shaft of a speedreducer 20, as through a plurality of V-belts 21.

A counterbalance cylinder 22 is swingingly attached to the beam as at2%, this cylinder having a Working barrel 2'4 and a piston 25-. Thepiston speed shaft 3| of the reducing gear.

is mounted on a hollow piston rod 26 closed at its lower end as at 21and swivelling in a cupped socket 28.

An air cushion maintained in the cylinder at a suitable pressurecounterbalances the weight of the rod string plus approximately one-halfthe weight of the oil column in the pump tubing, thus equalizing thepower load between the upstroke and the downstroke of the beam. Air isadmitted to the cylinder, to offset leakage and for the purpose ofrepressuring, conveniently through a flexible tube 29 connected with thelower end of the hollow piston rod. A valve-controlled vent 29A permitsthe pressure in the cylinder to be reduced or released as may berequired.

To this point the description is of an apparatus in common use, thisdescription providing merely the environment in which the novelcombination of elements next to be described is utilized.

Referring now to Fig. 2, a drive plate 30 is nonrotatably mounted on theouter end of the high Pulley I9 is provided with a plurality of groovesfor the main drive belts 2| and with ordinarily a single groove for aV-belt 32 which drives an air controlled clutch generally indicated at33 and through it an air compressor 34 which is preferably aconventional two-cylinder unit compressing in stages. Pulley I9 ismounted to rotate freely on shaft 3|, as on roller bearings 35, anddrive plate 30 is keyed to the shaft as at 36.

The drive plate is provided with a plurality of readily removable studs31 which project into registering holes in the web of pulley 19. Withthese studs in position the pulley is keyed to the drive plate andactuates the beam, while with the studs withdrawn the prime mover may beused to drive the compressor without actuating gear set, cranks andbeam.

This simple arrangement of drive plate and studs is the functionalequivalent of a jaw clutch, which may be substituted if preferred.

The clutch through which compressor 34 is driven must be of a type whichis engaged and disengaged by changes in air pressure, and must furtherbe so arranged that the clutch is engaged when the air pressure in thecylinder is low or atmospheric and disengaged by rising air pressure. Asuitable form for this clutch is generally indicated at 33 and will nowbe described, it being understood that this detail is illustrative only.

An enlarged projection of the compressor crank shaft 38 is extendedthrough a U-frame 39 in which it is carried on antifriction bearings 40and 4!. A clutch spider 42 carrying on its face a ring of brake lining43 has a hub 44 slidable lengthwise on the shaft. The hub is preventedfrom rotating on the shaft by a through-pin 45 passed through adiametric slot 46. The hub is constantly urged to move to the limit ofits travel by a relatively stiff coil spring 41 bearing against a collar47A which is fixed to the shaft.

The end of the shaft distant from the compressor is drilled centrally toreceive a plunger 48 of which one end bears against pin 45, the otherend carrying a disc 49 on which bears a cup leather or other piston 50.The cup is slidable within a short, closed-end cylinder and is held incontact with the disc by a relatively light coil spring 52.

A V-belt pulley 53, having a groove for belt 32, is mounted to revolvefreely around shaft 38, as on radial-thrust bearings 54. The side ofthis pulley directed toward brake lining ring 43 is '4 faced smooth. Thepulley is coupled to main drive pulley I 9 by belt 32 (shown as brokenbecause of limitations of space) and rotates continuously, in a fixedlongitudinal position on shaft 38, so long as the prime mover I! of Fig.1 is in operation.

The compressor, which is indicated only in outline at 34, dischargesinto a relatively small air accumulator 55, from which the flexible tube29 conducts air under pressure into hollow piston rod 26 and thus intothe cushion space within counterbalance cylinder 22. Anarrow conduit 56,preferably containing in its length a balanced pressure valve 51, placesaccumulator 55 in communication with the space in cylinder 5| abovepiston 50.

Thus connected, when the pressure in the accumulator rises to apredetermined level, the piston 50, disc 49, plunger 48 and spider 42are forced inwardly, carrying the friction ring 43 out of contact withthe face of pulley 53 and effectively disconnecting the compressor fromits drive. When the pressure again falls, spring 41 returns the frictionring into contact with the constantly revolving pulley and thecompressor is again actuated. This arrangement must not be reversed asit is essential to repressuring that the compressor be coupled foractuation when there is no pressure in the air system.

The purpose of the balanced pressure valve 51 is to ensure sharp openingand closing of communication between the accumulator and the clutchcylinder, thus avoiding slipping and burning of the engaging members.This valve is an article of commerce and needs no description.

The combination above described, of a manually controlled clutch betweenthe speed reducer and a pulley constantly rotated by the prime mover,with a pressure-responsive clutch between an independent air compressorand a pulley constantly rotated by the prime mover, has materialadvantages over previously disclosed arrangements for providing make-upair and repressuring.

For example, the beam is idle during repressuring and thus it is notnecessary to disconnect the well load from the pumping unit torepressure the balancing cylinder. Taking the compressor drive from theprime mover avoids the necessity for a separate engine or motor to drivethat element. As the beam is idle during repressuring the prime movermay be speeded up, if desired, to drive the compressor at its maximumpermissible speed and thus the repressuring may be accomplished in abrief time even with a small and inexpensive compressor. Conversely, asmall compressor may be operated at high speeds for short periodswithout damage or undue wear, and as the provision of make-up airrequires the operation of the compressor for only brief and widelyspaced periods, the provision of the automatic clutch which completelydisconnects the compressor from its drive during the intervals betweenthese. periods of demand reduces the wear on this element in pumpingservice to almost negligible. Repressurizing the system with anindependent two-stage compressor eliminates the hazard of dieselizing.

Finally, except for the manual disconnection of the reducing gear fromthe main drive for the purpose of repressuring the operation of thesystem is entirely automatic. When repressuring is completed thecompressor stops. The prime mover is then stopped long enough to replacethe studs in the drive plate, or to engage an equivalent jaw clutch, andto attach the pump rod string to the swinging end of the beam. On againstarting the prime mover, pumping begins and the compressor comes intooperation only as small quantities of air are required from time to timeto maintain the pressure in the counterbalancing cylinder.

I claim as my invention:

1. Apparatus for providing make-up and repressuring air to the cylinderof an air-balanced deep well pumping unit actuated by a prime moverthrough a speed reducer, comprising: a pulley revolving freely on thehigh-speed shaft of said reducer; manually operable means for lockingsaid pulley to said shaft for synchronous rotation; an air compressorhaving a pulley mounted to revolve freely on an extension of itscrankshaft; a belt connecting said pulleys for synchronous rotation; aconduit connecting the discharge of said compressor with the interior ofsaid counterbalance cylinder, and clutch means responsive to thepressure in said conduit for locking second said pulley to saidcrankshaft for synchronous rotation, said clutch means being so arrangedas to render said compressor operative when the pressure in said conduitfalls below a predetermined level and to render said compressorinoperative When said pressure reaches said level.

2. Apparatus for providing make-up and repressuring air to the cylinderof an air-balanced deep well pumping unit actuated by a prime moverthrough a speed reducer, comprising: a pulley driven by said prime moverand normally driving said speed reducer; manually operable clutch meansbetween said pulley and said reducer for rendering said speed reducerinoperative while said pulley continues to revolve; an air compressorhaving a crankshaft and a drive from said pulley to said crankshaft; aconduit connecting the discharge of said compressor With the interior ofsaid counterbalance cylinder, and clutch means interposed between saidcrankshaft drive and said crankshaft and responsive to the air pressurein said conduit to disconnect said drive from said crankshaft when thepressure in said conduit reaches a predetermined level and to reconnectsaid drive with said crankshaft When said pressure falls below saidlevel.

3. Apparatus for providing make-up and repressuring air to the cylinderof an air-balanced deep Well pumping unit, comprising: a compressorhaving a crankshaft; a pulley rotatable around said crankshaft; a speedreducer having a drive shaft and a pulley rotatable therearound; anautomatic clutch responsive to the air pressure in said cylinderarranged to lock first said pulley in driving relation with saidcrankshaft when said air pressure falls below a predetermined level, andmanually operable means for connecting second said pulley in drivingrelation With said drive shaft.

WILLIAM G. COREY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,624,577 Brett Apr. 12, 19272,117,716 Gordy May 17, 1938 2,269,787 Saxe Jan. 13, 1942

